A function that returns an HTML string, DOM element(s), text node(s), or jQuery object to insert before each element in the set of matched elements. Receives the index position of the element in the set as an argument. Within the function, this refers to the current element in the set.

A function that returns an HTML string, DOM element(s), text node(s), or jQuery object to insert before each element in the set of matched elements. Receives the index position of the element in the set and the old HTML value of the element as arguments. Within the function, this refers to the current element in the set.

The .before() and .insertBefore() methods perform the same task. The major difference is in the syntax—specifically, in the placement of the content and target. With .before(), the content to be inserted comes from the method's argument: $(target).before(contentToBeInserted). With .insertBefore(), on the other hand, the content precedes the method and is inserted before the target, which in turn is passed as the .insertBefore() method's argument: $(contentToBeInserted).insertBefore(target).

Consider the following HTML:

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<divclass="container">

<h2>Greetings</h2>

<divclass="inner">Hello</div>

<divclass="inner">Goodbye</div>

</div>

You can create content and insert it before several elements at once:

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$( ".inner" ).before( "<p>Test</p>" );

Each inner <div> element gets this new content:

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<divclass="container">

<h2>Greetings</h2>

<p>Test</p>

<divclass="inner">Hello</div>

<p>Test</p>

<divclass="inner">Goodbye</div>

</div>

You can also select an element on the page and insert it before another:

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$( ".container" ).before( $( "h2" ) );

If an element selected this way is inserted into a single location elsewhere in the DOM, it will be moved before the target (not cloned):

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<h2>Greetings</h2>

<divclass="container">

<divclass="inner">Hello</div>

<divclass="inner">Goodbye</div>

</div>

Important: If there is more than one target element, however, cloned copies of the inserted element will be created for each target except for the last one.

Additional Arguments

Similar to other content-adding methods such as .prepend() and .after(), .before() also supports passing in multiple arguments as input. Supported input includes DOM elements, jQuery objects, HTML strings, and arrays of DOM elements.

For example, the following will insert two new <div>s and an existing <div> before the first paragraph:

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var newdiv1 = $( "<div id='object1'></div>" ),

newdiv2 = document.createElement( "div" ),

existingdiv1 = document.getElementById( "foo" );

$( "p" ).first().before( newdiv1, [ newdiv2, existingdiv1 ] );

Since .before() can accept any number of additional arguments, the same result can be achieved by passing in the three <div>s as three separate arguments, like so: $( "p" ).first().before( $newdiv1, newdiv2, existingdiv1 ). The type and number of arguments will largely depend on how you collect the elements in your code.

Дополнительные замечания:

Prior to jQuery 1.9, .before() would attempt to add or change nodes in the current jQuery set if the first node in the set was not connected to a document, and in those cases return a new jQuery set rather than the original set. The method might or might not have returned a new result depending on the number or connectedness of its arguments! As of jQuery 1.9, .after(), .before(), and .replaceWith() always return the original unmodified set. Attempting to use these methods on a node without a parent has no effect—that is, neither the set nor the nodes it contains are changed.

By design, any jQuery constructor or method that accepts an HTML string — jQuery(), .append(), .after(), etc. — can potentially execute code. This can occur by injection of script tags or use of HTML attributes that execute code (for example, <img onload="">). Do not use these methods to insert strings obtained from untrusted sources such as URL query parameters, cookies, or form inputs. Doing so can introduce cross-site-scripting (XSS) vulnerabilities. Remove or escape any user input before adding content to the document.